Concerning the microstructure changes that occur at the surface of UO2 pellets on irradiation to high burnup

Fuel-to-cladding gap evolution and its impact on thermal performance of high burnup fast reactor type uranium–plutonium oxide fuel pins

“…Tourasse et al [1] also reported that the amount of the retained gaseous FP in the fuel pellet showed a remarkable Ôdip' between 70 and 90 GWd/MTM corresponding to the JOG evolution. These observations are coincident with those on high burnup uranium dioxide fuels in thermal reactors reported by Walker et al [11] and Lassmann et al [12]. We will continue to investigate the JOG evolution scenario in conjunction with the dynamic changes of the gaseous FP release and retention behavior in future.…”

Microbeam analysis of irradiated nuclear fuel

“…The transformed microstructure (figure 6), which is termed the high burn-up structure, exhibits a pronounced decrease in grain size and high volume density of small facetted pores [25]. The driving force for re-crystallisation is generally accepted to be the build-up of stored energy resulting from the accumulation of radiation damage at low temperature [26,27].…”

Distributions of volatile fission products in or near the fuel-cladding gap of the FBR MOX fuel pins irradiated to high burn-up

“…2. A microstructure similar to the rim structure [12] seen in irradiated LWR fuel is observed. This means the sub-micron grain structure evolves from the as-fabricated grain structure, together with small sized pores.…”